Tagged Questions

A cipher which uses a different encryption key every time, as long as the message. The key is XOR'ed with the message to render the cipher text which can then be XOR'ed with the same key to get the plain text.

One time pad ciphers are unbreakable if the message is encrypted correctly and if only used once. However if used more than once, it becomes decipherable. How come?
Also, would it be smart to use one ...

I just have gotten into cryptography and learned about the Vigenère block. I think it's a very good idea because, if used correctly, it is unbreakable. But the only downsite is, the key must be the ...

Having shared a pad of length double the length of your anticipated message, splitting it into x and y.
Then using x to encrypt the message, and using y twice to encrypt the next pad, would that be ...

From what I could research, XORing a random key adds confusion.
But I do not undertand the rationale for that classification. Shannon's confusion is supposed to obscure the relationship between the ...

Is there something like a perfect asymmetric crypto-algo? Is there proof that there must be one or not. From a logical point of view it seems to be possible to design such algorithm if your keysize is ...

I encrypt 2 random keys with the same 'one' time pad. You can get both encrypted keys. You don't know anything besides the size.
Is there a way to attack the two time pad in this scenario?
And what ...

OTP encryption is unbreakable as it seems. I have read some stuff (wiki, blogpost, etc.) but i would not find any information how they are used.
If i wanted to create a messenger service, how would i ...

EDIT: This is not a duplicate, in this I have explained WHY this should be secure and not if it is secure, so please stop down-vote if you haven't read everything.
I have questioned before about my ...

EDIT: REUSING KEY IS SECURE! OTP - Reusing key IS SECURE! PROVED!
This might sound really dumb but why is it bad/insecure too use the same key twice on One-time-pad?
Question: Why and how does using ...

Recently I've been delving into security algorithms, I already knew some of the (easy) math behind AES and RSA and how to and not to implement it. But well, i got a bit bored so i thought I'd just do ...

We know that the one-time pad is provably secure as a cipher to encrypt some data. Is there an algorithm which does the same just as a hash function? Can we get a provably secure hash function? Maybe ...

I understand that by definition one-time-pad keys cannot be reused but I was thinking about the case where it is used to send random data and couldn't find anything on the subject so here is my idea:
...

One of the main rules of the OTP is, that a key should never ever be reused.
But if we use some commutative operation (XOR for example) for generating the cipher text, then I don't see any difference ...

I was playing with the Vernam cipher on some online converter.
But when I tried to encrypt my message string with numbers, it remained unchanged.
Moreover, it was ignoring numbers and was encrypting ...